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Discussion Starter · #1 ·
For those of you that might be interested, I got the mentioned resolution using the settings below.


Any suggestions and/or critics are really appreciated.


Note: HTPC with Radeon


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PowerStrip timing parameters:

1024x576=1024,31,64,209,576,32,24,109,70851,336


Generic timing details for 1024x576:

HFP=31 HSW=64 HBP=209 kHz=53 VFP=32 VSW=24 VBP=109 Hz=72


Linux modeline parameters:

"1024x576" 70.851 1024 1055 1119 1328 576 608 632 741 +hsync +vsync

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camoura
 

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The LT150 has a native resolution of 1024x768. If you send it a 1024x576 signal, it will have to scale it internally to 1024x768 anyways. Why not use your HTPC to output 1024x768 and leave it at that? The scaling performed by the Radeon should be better than the LT150's internal scaler. BTW, I like seeing the XF86Config settings!

 

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Pham,


I think you missed the point, hopefully 1024x576 turns the LT150 into a widescreen projector without the need for scaleing.If this works without it kicking in the internal scaler then I think this is a big deal.


Jeff
 

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Discussion Starter · #4 ·
Quote:
Originally posted by pham:
... If you send it a 1024x576 signal, it will have to scale it internally to 1024x768 anyways. Why not use your HTPC to output 1024x768 and leave it at that?

Are you sure about this scaling thing ?? Due to the halo, I can see the 4:3 panel boundries and the 16:9 image is inside this panel. Anyway, the projector is set to native resolution.



camoura


 

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Please explain further -- I don't see how this works. Since the LT150 has a 1024x768 DLP grid, if you want widescreen, you simply let your Radeon scale a widescreen picture to 1024x768. The picture uses the middle 1024x576 and leaves black bars at the top and bottom.


If you use the HTPC to scale to 1024x768, the projector has to either (a) scale this back to 1024x576, or (ii) position the signal in the middle of the 1024x768 grid. So why bother?


If there is some benefit to this, please let me know -- my HTPC should ship late this week.


[This message has been edited by Lurker #25 (edited 08-21-2001).]
 

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Lurker's right. Digital projectors always use their native resolution. For the LT150, this is 1024x768. You could use a 1024x576 window within the 1024x768 display by using the "native" mode, but then you would not be making full use of all the pixels within the panel. It makes more sense to let the HTPC do all the scaling.


JeffY, I actually thought the point was to use a good resolution for PAL discs. The only way to turn the LT150 into a widescreen projector would be to get a special lens like the Panamorph. In this case, you would STILL want to send 1024x768 to the projector, only with a "stretched" image so that the panamorph "squeezes" it, and outputs the correct aspect ratio.
 

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Discussion Starter · #7 ·
Quote:
Originally posted by Lurker #25:
Please explain further -- I don't see how this works. Since the LT150 has a 1024x768 DLP grid, if you want widescreen, you simply let your Radeon scale a widescreen picture to 1024x768. The picture uses the middle 1024x576 and leaves black bars at the top and bottom.


If you use the HTPC to scale to 1024x576, the projector has to either (a) scale this back to 1024x576, or (ii) position the signal in the middle of the 1024x768 grid. So why bother?


If there is some benefit to this, please let me know -- my HTPC should ship late this week.
The reason why I am using 1024x576 is because I prefer a 16:9 screen. Since the projector is for watching movies and most of them are at least 16:9, so why use a 4:3 screen. Anyway, If you like a 4:3 screen better, you should really use the native 1024x768.


I hope that, as you said, the LT positions the 1024x576 signal in the middle of the 1024x768 grid.


camoura
 

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Quote:
Originally posted by camoura:
I hope that, as you said, the LT positions the 1024x576 signal in the middle of the 1024x768 grid.
If you're using an HTPC at 1024x768 resolution, the dvd software will already place a widescreen image in the center of the 1024x768 grid. What is the benefit you're looking for by using 1024x576?
 

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Doesn't setting the 150 to cinema under aspect ratio accomplish this anyhow?


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Every man is my superior, in that I may learn from him.
 

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i've used 1024 x 576 resolution with my XGA projector (UP-1100 in widescreen mode) for two reasons:


1) this gives you an aspect-correct widescreen desktop.


2) when in widescreen mode, the projector scales the incoming signal to 576 lines, not the panel's native 768.

although sending in a 576 line signal doesn't bypass the internal scaler (at least on my unit,) it does result in a substantially sharper picture. the internal scaler is essentially scaling from 576 to 576 lines, introducing the least possible scaling artifacts, and the PC does a btter job of scaling to 576 in the first place...


 

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Yes but that would only work if you had a 4:3 screen, with a 16:9 screen you would end up using a tiny portion of the screen. 1024x576 gives you a widescreen desktop that uses the full size of a 16:9 screen. If you tried the same thing at 1024x768 it would work for 16:9 DVDs but the windows desktop wouldn't fit.


Jeff
 

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Quote:
Originally posted by packlet:
although sending in a 576 line signal doesn't bypass the internal scaler (at least on my unit,) it does result in a substantially sharper picture
The thing projects 1024x768 no matter how you cut it. There is no conceivable way I can imagine it would put out a sharper picture.


Just for kicks I made a .bmp exactly 1024x768 pixels with alternating white and black pixels like a checkerboard, to see how acurately it reproduces each one (thank God for copy and paste!). LT150 reproduced every one perfectly, of course. Now, I use a 16:9 screen, so there was spill over. Setting the GeForce to 1024x576 outputted the exact same pixel definition and structure with...less pixles! All it did was fill in the top and bottom of the DLP array with "off" pixels (black) instead of using the "black" from PowerDVD. The only room for improvement is maybe the "black" from the projector is 100% black, while the black from the VGA cable is 99.99% black from signal loss, etc (it is analog, after all)


It still projects a 4:3 Halo regardless, but your desktop perfectly fits in the 16:9 screen. User preference, I guess.


On a side note, I have yet to be able to use 72hz. 60hz and 75hz works great, but 72hz comes out very dark with dark green bands. Any ideas?


-Erik-


edit: it's .bmp! not .bpm! doh...



[This message has been edited by ferrocene (edited 08-21-2001).]
 

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Discussion Starter · #15 ·
Quote:
Originally posted by ferrocene:


On a side note, I have yet to be able to use 72hz. 60hz and 75hz works great, but 72hz comes out very dark with dark green bands. Any ideas?


I know you are using GeForce, but did you try my settings ?


camoura
 

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camoura-


Excellent! I think some of the folks here are missing the benefit of running a 1024x576 desktop. Right now I have a 16x9 screen and a LT-100 projector, which is 4x3. I have the unused portions of the 4x3 projector image masked off in front of the projector. It's great for movies, but I can't really use it for anything else, because I'm only seeing three quarters of the Windows desktop. I can't surf the web, or play MP3s, or really use any other non-video PC application. I have to use a desktop monitor, which doesn't have the "cool factor" of the big screen. A native 1024x576 desktop would remove that restriction. I'll have to try your settings on my LT-100, and see what happens.


Thanks-


Dave
 

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Ah, now I see what you're doing. It's for using the HTPC for non-DVD stuff on a 16x9 screen. I just might try it too!


I've got a 92" 16x9 screen on order. A 1024x576 desktop lets me use the HTPC for non-DVD apps without having to move the projector around. There would still be unused resolution above and below the screen, but I suppose it's the only way to cram a 16x9 signal through a 4x3 projector. Until I get a panamorph, anyway!


But I gotta tell you, all those powerstrip numbers are freakin' me out.

 

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When I try these numbers in powerstrip, I get a 16x9 desktop. But it is vitrual, and when I move the mouse near the right edge, the screen pans with the mouse. Also does this on the bottom, and the pan discovers garbage. Can someone help?


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Adam
 

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From the useless information department:


Cinema mode CAN be activated while using the RGB input. It engages the internal scaler of the LT-150 and makes the normally 4:3 desktop squished, though. If you use Girder, the serial plugin, the supplied .gir file and a serial cable, the AspectCinema command in the .gir file turns on Cinema mode. This file also includes discrete on/off codes and discrete native/auto scaler codes.


The control files, and where to get them, are mentioned here . Since I didn't produce this stuff, I'd suggest questions or requests for more function go there, too.


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Huck
 
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